/*
 * Copyright 2002-2004 the original author or authors.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.springframework.context.support;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.springframework.beans.BeansException;
import org.springframework.beans.factory.config.BeanPostProcessor;
import org.springframework.context.ApplicationContext;
import org.springframework.context.ApplicationContextAware;
import org.springframework.context.ResourceLoaderAware;

/**
 * BeanPostProcessor implementation that passes the application context to
 * beans that implement the ApplicationContextAware or ResourceLoaderAware
 * interfaces. If both are implemented, the latter is satisfied first.
 *
 * <p>Application contexts will automatically register this with their
 * underlying bean factory. Applications do not use this directly.
 *
 * @author Juergen Hoeller
 * @see ApplicationContextAware
 * @see AbstractApplicationContext#refresh
 * @since 10.10.2003
 */
public class ApplicationContextAwareProcessor implements BeanPostProcessor {

  protected final Log logger = LogFactory.getLog(getClass());

  private final ApplicationContext applicationContext;

  /**
   * Create a new ApplicationContextAwareProcessor for the given context.
   */
  public ApplicationContextAwareProcessor(ApplicationContext applicationContext) {
    this.applicationContext = applicationContext;
  }

  // ApplicationContext是ResourceLoader的子类型,
  // 所以这个BPP同时处理了ResourceLoaderAware与ApplicationContextAware
  public Object postProcessBeforeInitialization(Object bean, String name) throws BeansException {
    if (bean instanceof ResourceLoaderAware) {
      if (logger.isDebugEnabled()) {
        logger.debug("Invoking setResourceLoader on ResourceLoaderAware bean '" + name + "'");
      }
      ((ResourceLoaderAware) bean).setResourceLoader(this.applicationContext);
    }
    if (bean instanceof ApplicationContextAware) {
      if (logger.isDebugEnabled()) {
        logger.debug("Invoking setApplicationContext on ApplicationContextAware bean '" + name + "'");
      }
      ((ApplicationContextAware) bean).setApplicationContext(this.applicationContext);
    }
    return bean;
  }

  public Object postProcessAfterInitialization(Object bean, String name) {
    return bean;
  }

}
